Addition/Subtraction Method

For this method you need to multiply to get the y-value preferably the same in both the l1 and l2 columns. After doing this you subtract the l2 column from the l1 column. When you do this your y-value is gone so you should get the x-value to equal your answer part of your question. Then you divide your x value into the answer to get your answer. To check your answer you need to just plug in your answer that you got and it should equal out on both sides.